Wedding invitations for undisclosed location

I would put the pick up location on the invitations

I have to agree with all of Meagan's points below. Its fine to put the address of the pickup location, but how do guests leave the venue? Is it more about the parking challenges, or is it mostly concern about people drinking and driving?

If its about parking, I would put "Please visit our wedding website for directions and details", or something along those lines. You have more space on the wedding website to stress to guests that parking at the venue is scarce, and that transportation will be provided. List the location and pick up time(s), and provide details for how the heck they'll get home, because that would for sure be my first question as a guest. Some might prefer to have a DD, or maybe they'll prefer to grab a cab, what if they're running late and missed the bus? You still have to tell them where the venue is.

Be prepared for questions. This is pretty unorthodox and people will be confused.

If the main concern is drinking and driving...I mean....you know your crowd...but my feeling is that they're adults, and you can't control 120 or however many people. You can give them all the tools for getting home safely, but at the end of they day, they're going to make those decisions.

Our venue was an hour out of the city. We provided hotel and cab info, but we found that most guests still drove home, and just made plans for a DD.

Are you getting your guests picked up at one location? I would have that address on the invitations and a time to be there to by

I think people would start calling and asking where the venue is. i know i would. but are you picking up each person at their house specifically? how do you know if they are coming to both the ceremony and reception? what happens if theyre not ready when your car arrives?

Well invitations on Vista Print are customizable and you should be able to get rid of that line - but otherwise maybe you could list the place they are to meet up to catch the shuttle?

I definitely understand the disdain for driving under the influence. That said, I see some challenges with your plan even beyond the invitations.
How will you be ensuring all guests can leave when they want to?
Is everyone staying at the same hotel or are you wanting people to drive to a pickup location. If so, is there parking? Is it free? What if some are running late? As for the drinking and driving, wouldn't the transportation just take them back to their cars?
I wouldn't enjoy not knowing where I was going and being uncertain how and when I could leave. I would enjoy it even less if I found out this was because the host had such little faith in me that she felt I couldn't be trusted to not drink and drive.
This is what I would suggest:If the concern is about parking, come up with a solution for that. Maybe that includes locating parking 5 minutes away and you can just run a shuttle all night.
If the concern is about driving after drinking, consider a dry wedding. Or ensure bar staff are committed to not serving anyone who is impaired (they shouldn't anyway). Or have your reception at or near a hotel and encourage guests to book a room.
If you are really set on having a surprise location, I suppose you could enter the meeting location as the venue with the time they need to be there and then indicate they will be taken to a secret location.